DIY glass fibre plenum chamber? Bad idea?

[ECMnut at aol.com]

My Neon intake manifold is molded plastic.  Pretty wild looking.
I would stay away from fiberglass, due to the underhood heat.

Try fabbing something out of metal, and if you need to seal cracks
and seams, there is this neat stuff from Moroso called *racer poxy*
that is like clay.  There is the resin & the hardener.  They both have
a clay like consistency, but when you mix them, the stuff hardens to
a tough, somewhat heat resistant material that can be machined,
sanded painted, etc.  I have used it to shape intake ports where 
cross sectional reduction was needed.   NHRA Super stock and
modified racers have done it for years.  It's a great ''quick fix' if you
 go too far with a port grinder on the intake port or manifold..
You are even safer if you use the stuff externally to seal corners 
& gaps in your home made manifold.
GL Mike V